The plasma membrane traits ouabain-resistance and concanavalin A-resistance, properties of cells that differ in susceptibility to ethyl methanesulfonate (EMS), and also certain cellular properties related to in vitro transformation will be investigated in genetically oriented studies with cultured cells. Mutant human Hela and diploid fibroblast cells resistant to the Na ion/K ion ATPase inhibitor ouabain will be investigated further, with attention to gene dosage effects on K ion transport and ouabain-binding, purification and peptide mapping of affected enzyme, possible antigenic changes stemming from the alteration, and isolation and characterization of revertants. Concanavalin A-resistant mutants of Chinese hamster ovary cells that are temperature-sensitive for growth and defective in glycoprotein synthesis will be examined further with particular regard to the properties of revertants and of various hybrids. Isolates of Hela cells that differ in sensitivity to the mutagen EMS will be studied to compare alterations in response to killing and mutagenesis by EMS and other agents and to discover the basis for the different phenotypes. A system will be established for chromosome-mediated gene transfer between Hela and human diploid fibroblast cells of traits that comprise the transformed phenotype in vitro. New phenotypes so generated would be studied with a view to analyzing the component aspects of neoplastic transformation.